Spatial Distribution Pattern of Longhorn Beetle Assemblages (Coleoptera: Cerambycidae) in Mongolian Oak (Quercus Mongolica) Forests in Changbai Mountain, Jilin Province, China

Background: Mongolian oak forest is a deciduous secondary forest with a large distribution area in the Changbai Mountain area. The majority of longhorn beetle species feed on forest resources, The number of some species is also large, which has a potential risk for forest health, and have even caused serious damage to forests. Clarifying the distribution pattern of longhorn beetles in Mongolian oak forests is of great scientific value for the monitoring and control of some pest populations. Methods: 2018 and 2020, flying interception traps were used to continuously collect longhorn samples from the canopy and bottom of the ridge, southern slope, and northern slope of the oak forest in Changbai Mountain, and the effects of topographic conditions on the spatial distribution pattern of longhorn beetles were analyzed. Results: A total of 4090 individuals, 56 species, and 6 subfamilies of longhorn beetles were collected in two years. The number of species and individuals of Cerambycinae and Lamiinae were the highest, and the number of Massicus raddei (Blessig), Moechotypa diphysis (Pascoe), Mesosa myopsmyops (Dalman), and Prionus insularis Motschulsky was relatively abundant. Topographic conditions did not affect the vertical distribution of richness and abundance of longhorn beetles in the forest, but topographic conditions and vertical height independently affected the composition and quantity of the beetle assemblages. The community composition of longhorn beetles in the forest bottom and canopy was significantly different, and the richness and abundance were higher in the canopy under good light conditions. Cerambycinae and Lamiinae preferred to be active in the canopy, Prioninae preferred to be active in the forest bottom, and Lepturinae did not show any difference in the bottom and the canopy. Conclusions: The composition of the longhorn beetle community on the ridge was significantly different from that on the southern slope and the northern slope, and the richness and abundance on the ridge and the southern slope were higher than those on the northern slope. Different species had different preferences for topographical conditions and vertical height, which indicated the adaptability of longhorn beetles in the forest.

Generic Additive Allometric Models and Biomass Allocation for Two Natural Oak Species in Northeastern China

Current models for oak species could not accurately estimate biomass in northeastern China, since they are usually restricted to Mongolian oak (Quercus mongolica Fisch. ex Ledeb.) on local sites, and specifically, no biomass models are available for Liaodong oak (Quercuswutaishanica Mayr). The goal of this study was, therefore, to develop generic biomass models for both oak species on a large scale and evaluate the biomass allocation patterns within tree components. A total of 159 sample trees consisting of 120 Mongolian oak and 39 Liaodong oak were harvested and measured for wood (inside bark), bark, branch and foliage biomass. To account for the belowground biomass, 53 root systems were excavated following the aboveground harvest. The share of biomass allocated to different components was assessed by calculating the ratios. An aboveground additive system of biomass models and belowground equations were fitted based on predictors considering diameter (D), tree height (H), crown width (CW) and crown length (CL). Model parameters were estimated by jointly fitting the total and the components’ equations using the weighted nonlinear seemingly unrelated regression method. A leave-one-out cross-validation procedure was used to evaluate the predictive ability. The results revealed that stem biomass accounts for about two-thirds of the aboveground biomass. The ratio of wood biomass holds constant and that of branches increases with increasing D, H, CW and CL, while a reverse trend was found for bark and foliage. The root-to-shoot ratio nonlinearly decreased with D, ranging from 1.06 to 0.11. Tree diameter proved to be a good predictor, especially for root biomass. Tree height is more prominent than crown size for improving stem biomass models, yet it puts negative effects on crown biomass models with non-significant coefficients. Crown width could help improve the fitting results of the branch and foliage biomass models. We conclude that the selected generic biomass models for Mongolian oak and Liaodong oak will vigorously promote the accuracy of biomass estimation.

Phenological Changes of Mongolian Oak Depending on the Micro-Climate Changes Due to Urbanization

Urbanization and the resulting increase in development areas and populations cause micro-climate changes such as the urban heat island (UHI) effect. This micro-climate change can affect vegetation phenology. It can advance leaf unfolding and flowering and delay the timing of fallen leaves. This study was carried out to clarify the impact of urbanization on the leaf unfolding of Mongolian oak. The survey sites for this study were established in the urban center (Mts. Nam, Mido, and Umyeon in Seoul), suburbs (Mts. Cheonggye and Buram in Seoul), a rural area (Gwangneung, Mt. Sori in Gyeonggi-do), and a natural area (Mt. Jeombong in Gangwon-do). Green-up dates derived from the analyses of digital camera images and MODIS satellite images were the earliest in the urban center and delayed through the suburbs and rural area to the natural area. The difference in the observed green-up date compared to the expected one, which was determined by regarding the Mt. Jeombong site located in the natural area as the reference site, was the biggest in the urban center and decreased through the suburbs and rural area to the natural area. Green-up dates in the rural area, suburbs, and urban center were earlier by 11.0, 14.5, and 16.3 days than the expected ones. If these results are transformed into the air temperature based on previous research results, it could be deduced that the air temperature in the urban center, suburbs, and rural area rose by 3.8 to 4.6 °C, 3.3 to 4.1 °C, and 2.5 to 3.1 °C, respectively. Green-up dates derived based on the accumulated growing degree days (AGDD) showed the same trend as those derived from the image interpretation. Green-up dates derived from the change in sap flow as a physiological response of the plant showed a difference within one day from the green-up dates derived from digital camera and MODIS satellite image analyses. The change trajectory of the curvature K value derived from the sap flow also showed a very similar trend to that of the curvature K value derived from the vegetation phenology. From these results, we confirm the availability of AGDD and sap flow as tools predicting changes in ecosystems due to climate change including phenology. Meanwhile, the green-up dates in survey sites were advanced in proportion to the land use intensity of each survey site. Green-up dates derived based on AGDD were also negatively correlated with the land use intensity of the survey site. This result implies that differences in green-up dates among the survey sites and between the expected and observed green-up dates in the urban center, suburbs, and rural area were due to the increased temperature due to land use in the survey sites. Based on these results, we propose conservation and restoration of nature as measures to reduce the impact of climate change.

Influence of Tree Vegetation on Soil Microbial Communities in Temperate Forests and Their Potential as a Proactive Indicator of Vegetation Shift Due to Climate Change

Unexpected vegetation shift is a serious problem caused by climate change, resulting in considerable damage to local communities. It is necessary to be continuously monitored, and the soil microbial community is expected to reflect the pressure on forest ecosystems due to climate change. We investigated soil bacterial and fungal communities in Odaesan at a four-year interval through eDNA meta-barcoding and analyzed the compositional and functional differences between forest types (Mongolian oak (Quercus mongolica) forest with and without Manchurian firs (Abies holophylla)) and sampling years. As a result, denitrifiers predominated in the presence of Manchurian firs, but there was no difference in the influence of climate change by forest type. Although tree vegetation remained stable, the microbial communities significantly changed over four years. This result demonstrates that climate change significantly shifts the microbial communities, even if not enough to trigger a vegetation shift, thus a microbial indicator can be developed to assess the press disturbance accumulated on the forest ecosystem. Through this study, we identified the influence of Manchurian firs and that of climate change on soil microbial communities in temperate forests and demonstrated the potential of the microbial community as a proactive indicator of vegetation shift due to climate change.

Generic additive allometric models and biomass allocation for two natural oak species in northeastern China

Background: Accurate quantification of forest biomass through allometric equations is crucial for global carbon accounting and climate change mitigation. Current models for oak species could not accurately estimate biomass in northeastern China, since they were usually established limited to Mongolian oak (Quercus mongolica) on local sites, and specifically, no biomass models were available for Liaodong oak (Quercus wutaishanica). The goal of this study was, therefore, to develop generic biomass models for both oak species on large scale and evaluate biomass allocation patterns within tree components. Results: The stem biomass accounts for about two-thirds of the aboveground biomass. The ratio of wood biomass holds constant and that of branch increases with increasing D, H, CW, CL, while a reverse trend was found for bark and foliage. The root-shoot ratio nonlinearly decreased with D, ranging from 1.06 to 0.11. Tree diameter proved to be a good predictor, especially for root biomass. Tree height is more prominent than crown size for improving stem biomass models, yet it puts negative effects on crown biomass models with non-significant coefficients. Crown width could help improve fitting results of branch and foliage biomass models. Conclusion: We conclude that the selected generic biomass models for Mongolian oak and Liaodong oak will vigorously promote the accuracy of biomass estimation.

Monitoring for Changes in Spring Phenology at Both Temporal and Spatial Scales Based on MODIS LST Data in South Korea

This study aims to monitor spatiotemporal changes of spring phenology using the green-up start dates based on the accumulated growing degree days (AGDD) and the enhanced vegetation index (EVI), which were deducted from moderate resolution imaging spectroradiometer (MODIS) land surface temperature (LST) data. The green-up start dates were extracted from the MODIS-derived AGDD and EVI for 30 Mongolian oak (Quercus mongolica Fisch.) stands throughout South Korea. The relationship between green-up day of year needed to reach the AGDD threshold (DoYAGDD) and air temperature was closely maintained in data in both MODIS image interpretation and from 93 meteorological stations. Leaf green-up dates of Mongolian oak based on the AGDD threshold obtained from the records measured at five meteorological stations during the last century showed the same trend as the result of cherry observed visibly. Extrapolating the results, the spring onset of Mongolian oak and cherry has become earlier (14.5 ± 4.3 and 10.7 ± 3.6 days, respectively) with the rise of air temperature over the last century. The temperature in urban areas was consistently higher than that in the forest and the rural areas and the result was reflected on the vegetation phenology. Our study expanded the scale of the study on spring vegetation phenology spatiotemporally by combining satellite images with meteorological data. We expect our findings could be used to predict long-term changes in ecosystems due to climate change.